1. Field of the Invention
The present invention relates to integrated circuit packages and, more particularly, to integrated circuit packages that include stacked integrated circuits.
2. Description of the Related Art
As the trend for memory integrated circuit (IC) packages to be smaller and their memory density to be larger continues, advancements in packaging integrated circuits are needed. One recent advancement involves stacking multiple integrated circuit dies within a single IC package. In one approach, such stacking involves stacking a smaller die on a larger die. Each of the dies is wire bonded to a substrate. The use of wire bonding necessarily requires that access to bonding pads of each of the dies be available; consequently, the upper die, when stacked on the lower die, must be small so as to not inhibit access to the bonding pads of the lower die. This type of stacking has, for example, been used with same function dies (e.g., two Flash memory dies) or different function dies (e.g., one Flash memory die and one SRAM die). Stacking of two or three dies has been done for stacked Chip Scale Packages (stacked CSP) and stacked Thin Small Outline Packages (TSOP). In another approach, like-sized dies can be stacked by placing a spacer, namely a relatively thick insulator, between the dies. Although the spacer provides the lower die with sufficient space so that it can be wire bonded, the spacer disadvantageously makes the integrated circuit package thicker.
Unfortunately, conventional approaches to stacking multiple dies within an integrated circuit package either require that the upper die be substantially smaller than the lower die on which the upper die is stacked or inefficiently consume package thickness. As a result, the conventional approaches are not suitable for use when the multiple dies are the same size and resulting package thickness is important. Accordingly, there is a need for improved approaches to stacking multiple dies within an integrated circuit package.